“…This study addresses recent calls for more diverse sources of data in variationist work (e.g., Stanford, 2016). An important contribution of this study is the understanding of Basque ergative variation as orderly heterogeneity—a variable linguistic feature that, despite having received extensive attention in syntactic theory (Preminger, 2012; Rezac, Albizu, & Etxepare, 2014), language acquisition (Austin, 2007, 2013; Ezeizabarrena, 2013; Rodríguez-Ordóñez, 2015), and language processing (Díaz, Erdocia, de Menezes, Mueller, Sebastián-Gallés, & Laka, 2016; Zawiszewski & Laka, 2020; Zawiszewski, Gutiérrez, Fernández, & Laka, 2011), remains understudied from a quantitative sociolinguistic perspective. In this study, we draw from various traditions (formal linguistics, typology, and variationist approaches to subject production) to account for the structured variation of the -k ergative marker in Basque, which we show is constrained by the following linguistic factors: verb type, animacy, person and number of the subject, and phonological context.…”